In the manufacture of tires, various irregularities and variations in the dimensions in the tires can arise. For example, dimensional irregularities can arise from inaccuracies in the molding process, changes in the characteristics of the materials and compounds employed in manufacturing the tires, inaccurate centering and variations in the vulcanization process, etc. All of the possible irregularities and variations in the tires, which can arise during manufacture, either singularly or through interaction with one another, can cause eccentricity, static and dynamic unbalance in the tire, and force variation which can result in tire vibration or noise during use.
It is possible to correct many of these irregularities by first measuring the tire variations and applying various corrective actions to the tire. To measure the variations, the tire is placed in a tire uniformity inspection machine. In currently available tire uniformity inspection machines, testing is fully automatic. Tires are fed by conveyor to a test station where each tire is mounted upon a chuck, inflated to a predetermined pressure and rotatably driven at a standard speed with its tread surface in abutting contact with the circumferential surface of a loadwheel. The loadwheel is instrumented with load cells that measure forces due to the tire acting on the loadwheel in directions of interest. The data gathered during the testing process may be used to grade the tire and/or to take immediate corrective action via shoulder and tread grinders, which selectively grind rubber from regions of the tire to compensate for the variations detected during the testing process. Alternately, or additionally, the data taken during the testing cycle may be used to mark specific regions of the tire to alert the installer to an area of interest, such as an irregularity or point of high force in the tire, which will enable the installer to take corrective or compensating action during the installation of the tire onto a wheel.
In the typical tire uniformity testing machine available today, a vertically-movable lower rim is supported in the base of the machine and is mounted for movement towards and away from a fixed, motor driven spindle mounted to the top of the machine. An elaborate framework including a plurality of spaced apart columns supports the tire testing equipment as well as sensing, grinding and marking equipment. Many of the current machines when fully outfitted with a full compliment of subassemblies are very difficult to service and require great effort to convert from one tire size to another. In at least some of the currently available machines, the various subcomponents, such as grinders, sensors and marking equipment, are not well integrated because they were added to the basic structure over the course of time. Cabling for both power and control signals between the various components and a basic control panel can be very complex and difficult to troubleshoot should problems arise.
In still other testing machines, the level at which tires are tested at the testing station is well above the plant floors so as to require maintenance workers and operators to use auxiliary equipment, such as ladders or other devices, to reach componentry needing adjustment or service.